The present invention relates to cross-connect switches for use in data networks. In particular, it relates to a cross-connect switch which can connect computers to various networks using different protocols.
DISCUSSION OF THE RELATED ART
Computer networks have expanded greatly in terms of numbers of computers connected to a network and the types of networks which exist. In fact, a single computer may be part of several networks with different capabilities. Networks also have various numbers of computers, from work groups, to local area networks, wide area networks, and global networks, such as the Internet and world wide web. With so many types of networks created by various companies, different protocols are used for communications. Examples of these protocols include RS 232, Ethernet, Fast Ethernet, Token Rings, and ISDN. These protocols not only require special communications software, but also have specific hardware connection requirements. The hardware connection requirements necessitate various interconnections between computers, servers, routers and other physical equipment in order to implement the selected protocols and communications.
In order to provide the necessary connections, offices are now wired for computer network connections. Typically, cables run horizontally across a floor to interconnect the computers on that floor. Various networking equipment, such as routers, hubs and bridges, are located within a wiring closet on the floor. The networking equipment in the wiring closets on different floors are interconnected with vertically running cables. The horizontal cables typically terminate at a patch panel within the wiring closet. The networking equipment also terminate in a patch panel. To provide a specific computer with a connection to the network, the appropriate locations within the patch panels are interconnected with patch cords.
When a user changes locations, the physical interconnections must also be changed to provide the user with access to the same network equipment. Frequent changes in workforce and work space has resulted in significant changes to networks. These changes require multiple accesses to the interconnections, and complicated interconnections. Such changes also increase the costs of maintaining a network and are likely to cause more frequent faults. Therefore, a need exists for a system which allows automated interconnections of computers and networks.
Several different systems have been proposed for automating connections in a wiring closet through the use of cross connect switches. However, each of these systems include protocol specific hardware for making the connections. Thus, if a single network is used, the computers can be easily rearranged; but if more than one network is part of the system, as in today""s multi-protocol corporate data networks, automated changes in configurations are not possible. Plug-in cards (or equivalent hardware) of various types are used to interconnect the computers. Each plug-in card is designed for a specific communication protocol. When a computer is to be connected to a different network, the plug-in card for that computer has to be changed. Therefore, a need exists for an automated interconnection system which can operate with different protocols.
The present invention in great part overcomes the deficiencies of existing interconnection systems by providing a cross-connect switch which is operable with different protocols. According to one aspect of the invention, each device is connected to the interconnection system by programmable input/output (I/O) blocks. The I/O blocks include circuitry for executing different types of connections. Each I/O block has four differential pair inputs or outputs. The I/O block can use any set of these pairs, so as to accommodate different network protocols on different pairs.
According to another aspect of the invention, the I/O blocks provide for selective termination of each of the differential pairs. According to another aspect of the invention, the I/O blocks include circuitry to account for phantom current, half-duplex operation, and insertion losses.
According to another aspect of the invention, the I/O blocks are connected together through two crosspoint modules, one for transmission and one for reception. An output of each distribution side I/O block is connected to the transmit crosspoint module, and an input to the receive crosspoint module. The I/O blocks on the equipment side of the switch are connected to the crosspoint modules in reverse. Thus, by appropriately setting the connections in the cross point module, each computer on the distribution side can be connected to the appropriate network equipment on the equipment side. The crosspoint modules can be implemented as analog switches or digital routers, with sufficient bandwidth to accommodate different protocols.